Remarkably variable dielectric and magnetic properties of poly(vinylidene fluoride) nanocomposite films with triple-layer structure

The variable dielectric and magnetic properties of poly(vinylidene fluoride) (PVDF) nanocomposite films with triple-layer structure and with electrically conductive multi-walled carbon nanotubes (MWCNTs) and magnetic iron oxide (Fe3O4) nanoparticles as fillers, and PVDF as polymer matrix are systematically investigated. The single layer of MWCNTs/PVDF, Fe3O4/PVDF, and pure PVDF is denoted as A, B and P, respectively. The multilayered films with different arrangements are prepared by a simple two-step method. Scanning electron microscopy (SEM) shows good adhesion between the layers after stacking. The experimental results indicate that triple layer AAA films have higher dielectric constant (ε) and lower dielectric loss (tan δ) than the single layer A film with the same thickness in the frequency range of 102–104 Hz due to the interfacial effect. The nanocomposite films with structure of ABA and APA keep low tan δ when the filler content is high due to the intermediate B and P layer as an inter-barrier to prevent the formation of conductive network in these samples. To replace the intermediate B layer of BBB films by A layer produces much higher saturation magnetization (Ms) for the filler content above 2.0 wt% due to the synergistic effect. But the replacement of the B layer by P layer causes nearly no significant change of Ms. This work demonstrates a new method to tune the dielectric and magnetic properties of nanocomposites.